The expression tertiary-alkyl designates a saturated hydrocarbon radical having a tertiary carbon which carries ethyl or methyl radicals independently of one another. If the tertiary carbon carries only methyls, the tertiary-alkyl radical is tertiary-butyl. In the description which follows, only the tertiary-butyl radical will be discussed as an example of the tertiary-alkyls envisaged by the description; however, the use of one example as a means to describe the process is not intended to limit the scope of protection to only one species.
It is well known in the art to prepare ditertiary-butyl dicarbonate, (BOC).sub.2 O, from tertiary-butyl carbonate and phosgene, such as described by J. H. Howe in the Journal of Organic Chemistry 27, 1901 (1962). However, industry avoids the use of phosgene due to safety problems.
It is also known to prepare tertiary-butyl dicarbonate by condensing tertiary-butyl carbonate with an acid chloride in a mixture of toluene and dimethylformamide as disclosed by the article published by Pozdev, Smirnova Podgornova, Zentsova and le Kalei in Zhurnal Urganicheskoi Khimii, volume 15, No. 1, pages 106-109, in 1979 and translated in the Journal of Organic Chemistry USSR 1979, page 95. However, when we reproduced these experiments, the yields of tertiary.-butyl dicarbonate obtained were not satisfactory.